1. Field of the Invention
The present invention relates to a method for producing a reinforced block material of a crystalline material such as a metal or the like. More particularly, the present invention relates to a method for producing a reinforced material of a metal or the like from a crystalline material such as a metal or the like which heretofore has been formed in fiber-like or film-like shape only by making it amorphous or crystallized in a miniaturised grain structure.
2. Description of the Prior Art
Although a crystalline material should have an excellent strength primarily normal to the crystal, this, heretofore can only be accomplished in practice in an extremely fine range. It is an important problem how to widen such range of ideal strength. For example, although a crystalline polymer has the potential to have a far larger strength than a metal, it has, in practice only achieved strength in the order of about 1/100 of its potential. In order to reinforce the strength of such polymer, it has been the practice to allow the molecules to be oriented by elongation under specified conditions and put the orientation of the crystal in order. In the case of a metal, it is in a state far from the ideal strength due to such causes as the lattice defects, dislocation, or intercrystalline weakening in the crystal grains. A method for bringing the strength of such metals closer to the ideal strength involves making the crystals needle-like (whisker) containing no dislocations, or making the crystal grains be miniaturised, or glass-like containing almost no crystal. As the methods generally known for making metal crystal grains miniaturised as mentioned above, there are such ones as the addition of a crystal grain miniaturising agent to the molten metal. Physical deformation of the bulk material by extrusion, forging, rolling, etc., or powder metallurgy utilizing rapidly cooled metal powders.
However, the reinforcing method such as, for example, by the elongation of crystalline polymers is limited in the case of fibers only, and the method for molding these into a block-like form has not been obtained. Also, in the case of a metal, neddle crystals (whisker) become very expensive in cost and can not be applied in the case of a large sized block material. The reinforcing of a metal by crystal grain miniaturization can be said to be an excellent reinforcing method as it accompanies no lowering of elongation properties found in other reinforcing methods. However, the addition of crystal miniaturising agents to a molten metal has a limit in the miniaturization ability, and is considerably influenced by the cooling rate of the molten metal. Also, because the procedures of extrusion, rolling, forging, and the like which were effected with the object of deforming and pulverising the already formed crystal grains formed by physically deforming a bulk material are effected for a coagulated metal, such procedures required very large energy and high cost, and the deformed crystal grains, when left as they are, take flat shape equally in most cases, so that anisotropy in strength. Moreover, cracks were apt to occur in the material due to the deformation, and the exhaustion of the die members are hastened. Further, in the powder metallurgical method, not only do the crystal grains recrystallised in practice in sintering become large to a certain extent, but also, powder metallurgy has many procedures requiring high cost, mature consideration is required in the utilization of such material as a raw metal material, not only from the raw material costs, but also in the application to molded articles.